What is "beta particle"

alt. (context particle English) An energetic electron or positron produced as the result of a nuclear reaction or nuclear decay. n. (context particle English) An energetic electron or positron produced as the result of a nuclear reaction or nuclear decay.

n. a high-speed electron or positron emitted in the decay of a radioactive isotope

A beta particle, sometimes called beta ray, denoted by the lower-case Greek letter beta (β), is a high-energy, high-speed electron or positron emitted in the radioactive decay of an atomic nucleus, such as a potassium-40 nucleus, in the process of beta decay. Two forms of beta decay, β and β, respectively produce electrons and positrons. Beta particles are a type of ionizing radiation.